From viewpoints of environmental preservation and energy conservation, an engine that is a power source mounted on a vehicle such as an automobile is required to have high efficiency and exhaust gas purification. For the high efficiency, it is effective to improve combustion performed in a combustion chamber inside the engine. As that means, there is lean combustion that burns air-fuel mixture leaner than a stoichiometric air-fuel ratio of fuel and air, exhaust gas recirculation (EGR) combustion (hereinafter referred to as EGR combustion) that re-suctions (also referred to as refluxes) exhaust gas discharged from a combustion chamber into the combustion chamber by burning air-fuel mixture in the combustion chamber and burns the air-fuel mixture diluted by the exhaust gas, or the like.
However, in the combustion that aims to achieve such high efficiency, the combustion stability is deteriorated according to an operating state or an environmental condition. Therefore, a situation that cannot obtain high efficiency and low exhaust performance, at which the combustion can occur, may occur according to a condition.
To address such a problem, for example, PTL 1 discloses a fuel injection control device for an internal combustion engine having an in-cylinder fuel injection device, the fuel injection control device including: a jetting division ratio setting means for setting a jetting division ratio of an amount of fuel injected during an intake stroke to an amount of fuel injected during a compression stroke according to an operating state or an environmental condition of the internal combustion engine; and an operating means for injecting part or all of the required fuel during the intake stroke according to a set jetting division ratio and operating an in-cylinder fuel injection device so as to inject the remaining fuel during the compression stroke, in which, in a case where it is determined that the temperature of the air suctioned into the cylinder is higher than the temperature of the fuel injected from the in-cylinder fuel injection device, the jetting division ratio setting means sets the jetting division ratio so as to increase the ratio of the amount of the fuel injected during the intake stroke, as compared with a case where it is determined to be lower.
According to the prior art disclosed in PTL 1, in a case where the temperature of the air suctioned into the cylinder is higher than the temperature of the fuel injected from the in-cylinder fuel injection device, the fuel tends to be atomized by contact with high temperature air, and in such a situation, the amount of fuel attached to a wall surface of the cylinder decreases and the attached fuel also easily evaporates. Conversely, in a case where the temperature of the air suctioned into the cylinder is lower, the jetting division ratio is set so as to increase the ratio of the amount of the fuel injected during the compression stroke, as compared with the case where the temperature of the air suctioned into the cylinder is higher. Thus, it is possible to reduce the amount of the fuel attached to the wall of the cylinder without being vaporized.